Freon is a trademarked name for a specific coolant made by Dupont. I'm sure it was R-134, not freon. Using a home fill kit with only a gauge on the low side is a sure way to mess up the system. You really need it hooked up to a full manifold set of gauges that includes high and low pressure gauges. In addition, a thermometer is key to knowing how much pressure is in the system, since gases increase in volume and pressure as temperatures go up.
In your case, the sudden rise in pressure could have been from inverting the can and letting liquid flow into the system. Now that time has passed, a manifold set of gauges can identify if iit's overcharged, filter blocked, etc.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI